You have an amazing tank; thank you for sharing. Your cardinal and rummy nose tetras look colorful and active. Unless you got great deals on your fish it looks like you have quite a bit of money invested in those schools.

How large are the roseline sharks? Do you notice that they pick on the weakest fish of the group?

I started with six about two years ago. Lost one the first 24 hours, then the next two died at about 6-8 month intervals. While all the others grow larger, one always seems to stay the same size and waste away. It seems like they all eat enough, but the smallest always seems to be out casted from the group. The three that are left (after I lost the most recent one this week) are all 4-5" and robust.

Could you please share your experience with these great looking barbs.

I'm glad that you like my tank . I haven't as much as one might think. Rummynose and cardnial can be $3 a piece, so a group of 20+ can get quote expensive. The people that I deal with always give me great deals, especially when I buy in bulk. I pay about a $1.50 per fish.
As far as the roseline sharks go, they are about 4-5". I find that my experience with them is a little different then you had. I originally started with a group of 8 and had them for a 1+ years. In my experience these fish are always hungry and didn't show any aggression toward each other what so ever. They would always shoal and stay together. Now mind you that they are all the same size. About 2 months ago I accidently overdosed on Melafix ( DO NOT OVERDOSE) when my angelfish had rough fins from fighting and lost 3 Roseline Sharks and 3 Cardinals. I was devastated!!!! Now I have 5 and hoping to get some more. Since I'm probably going to get smaller
one's i'll share my experience with you once i get them.